The study, by the Disparities Solutions Center, affiliated with Harvard University and Masschusetts General Hospital, is the first to deal with unconscious racial bias and how it can lead to inferior care for African-American patients. It was published in the online edition of the Journal of General Internal Medicine.

The doctors in the study were told two men, one white and one African-American, were each 50 years old and complained of chest pain. Each showed other symptoms of a heart attack.

The result was most of the doctors were more likely to prescribe a potentially life-saving, clot-busting treatment for the white patients than for the African-American patient.

"Physicians, like others in the U.S., in this country, demonstrated unconscious biases based on race," said Massachusetts General Hospital chief researcher Alexander Green.

According to the study, those biases affected the treatment the doctors would have given the two patients.

The patients were not actually real people, but rather computer-generated images seen by the doctors only on a monitor.

This isn't the first study to find that whites get better medical care than blacks.

National Medical Association president Dr. Albert Morris said it has been demonstrated multiple times in the past that whites receive better care and get care sooner than their African-American counterparts.

This study differs from previous ones because it is the first to demonstrate the reason for the difference really is racial bias.

After the doctors in the study evaluated the two simulated patients, they were then given a so-called implicit association test. The test is designed to reveal a person's unconscious views of blacks and whites.

"If you scored high on the bias against African-Americans portion of the test, then you were actually less likely to provide clot-busting treatment for a heart attack for black patients," Green said.

The stronger a doctor's hidden anti-black feelings, the less likely he or she would be to give the black patient the clot-busting agent.

The drugs were considered one of the most effective treatments for the symptoms these doctors were presented with.

Green said administering the clot-busters can mean the difference between life and death.

The hope that doctors who hear about this report will learn to stop, think and consciously suspend their racial prejudices the next time they have to make a critical decision about a patient.

Black doctors also showed bias against the black patients, though less than white doctors.